

使用Ajax的最大优点就是能在不更新整个页面的前提下维护数据。这使得Web应用程序更为迅捷地响应用户交互,并避免了在网络上发送那些没有改变的信息。
Ajax不需要任何浏览器插件,但需要用户允许JavaScript在浏览器上执行。就像DHTML应用程序那样,Ajax应用程序必须在众多不同的浏览器和平台上经过严格的测试。随着Ajax的成熟,一些简化Ajax使用方法的程序库也相继问世。同样,也出现了另一种辅助程序设计的技术,为那些不支持JavaScript的用户提供替代功能。
对应用Ajax最主要的批评就是,它可能破坏浏览器后退按钮的正常行为(参见Jakob Nielsen’s的《Web设计10大错误(1999年)》)。在动态更新页面的情况下,用户无法回到前一个页面状态,因为浏览器仅能记忆历史记录中的静态页面。一个被完整读入的页面与一个已经被动态修改过的页面之间的差别非常微妙;用户通常会希望单击后退按钮能够取消他们的前一次操作,但是在Ajax应用程序中,这将无法实现。开发者们想出了种种办法来解决这个问题,大多数都是在用户单击后退按钮访问历史记录时,通过创建或使用一个隐藏的IFRAME来重现页面上的变更。(例如,当用户在Google Maps中单击后退时,它在一个隐藏的IFRAME中进行搜索,然后将搜索结果反映到Ajax元素上,以便将应用程序状态恢复到当时的状态。)
一个相关的观点认为,使用动态页面更新使得用户难于将某个特定的状态保存到收藏夹中。该问题的解决方案也已出现,大部分都使用URL片断标识符(通常被称为锚点,即URL中#后面的部分)来保持跟踪,允许用户回到指定的某个应用程序状态。(许多浏览器允许JavaScript动态更新锚点,这使得Ajax应用程序能够在更新显示内容的同时更新锚点。)这些解决方案也同时解决了许多关于不支持后退按钮的争论。
进行Ajax开发时,网络延迟——即用户发出请求到服务器发出响应之间的间隔——需要慎重考虑。不给予用户明确的回应,没有恰当的预读数据,或者对XMLHttpRequest的不恰当处理,都会使用户感到延迟,这是用户不希望看到的,也是他们无法理解的。通常的解决方案是,使用一个可视化的组件来告诉用户系统正在进行后台操作并且正在读取数据和内容。
对程序员而言,开发Ajax应用最头痛的问题莫过于以下几点:
DellTM AximTM Latitude D820 笔记本电脑
Armour College of Engineering
Department of Biomedical Engineering
Department of Chemical and Environmental Engineering
Department of Civil and Architectural Engineering
Department of Electrical and Computer Engineering
Department of Mechanical, Materials, and Aerospace Engineering
College of Science and Letters
Department of Applied Mathematics
Department of Biological, Chemical, and Physical Sciences
Department of Computer Science
Lewis Department of Humanities
Department of Math and Science Education
Department of Social Sciences
Graduate Programs in Public Administration
Chicago-Kent College of Law
Center for Access to Justice & Technology
Global Law and Policy Initiative
Institute on Biotechnology and the Human Future
Institute for Law and the Humanities
Institute for Law and the Workplace
Institute for Science, Law and Technology
College of Architecture
Institute of Psychology
Institute of Design
Institute of Business and Interprofessional Studies
Department of Undergraduate Business
Interprofessional Projects Program
IIT Leadership Academy
Ed Kaplan Entrepreneurial Studies Program
Jules F. Knapp Entrepreneurship Center
Stuart Graduate School of Business
Center for Financial Markets
Center for Professional Development
Information Technology and Management Degree Programs
Industrial Technology and Management Degree Programs
Professional Learning Programs (CEU/Adult Education)
History
Armour Institute of Technology
One of IIT’s predecessor institutions, Armour Institute of Technology, was founded with a gift from Philip Danforth Armour, Sr., a prominent Chicago meat packer and grain merchant. Armour had heard Chicago minister Frank Gunsaulus say that with a million dollars, he would build a school that would be open to students of all backgrounds, instead of just the elite as was common then. This became known as the Million Dollar Sermon. After the sermon, Armour approached Gunsaulus and asked if he was serious about his claim. When Gunsaulus said yes, Armour told him that if he come by his office in the morning, he would give him the million dollars. Armour also stipulated that Gunsaulus become the first president of the school, and Gunsaulus served as president of Armour Tech from its founding in 1893 until his death in 1921.
Centered at 33rd Street and Armour Avenue (now Federal Street), Armour Institute of Technology shared the neighborhood now known as Bronzeville with many historic places – Old Comiskey Park sat just a few blocks away, west of what is now the Dan Ryan Expressway; the land used to expand the campus in the 1940s through 1970s was home to many of Chicago’s old famous jazz and blues clubs, with performers like Louis Armstrong highlighting the neighborhood; and, as evidenced by the affluent church in which Gunsaulus ministered and the Armour family attended, some of Chicago’s most influential members frequented the area.
Lewis Institute
Founded in 1895 by the will of Chicago real estate investor Allen C. Lewis, Lewis Institute stood where the United Center now stands. Lewis was one of many real estate investors to descend on Chicago after the Great Chicago Fire of 1871, and helped to rebuild the city’s west side. The Institute, under its first director, George Noble Carman, quickly became a pioneer in education, offering adult education programs that were well before their time. The Institute offered courses in engineering, sciences, and technology, but also featured courses in home economics and other domestic arts. One unique program featured a young child "borrowed" from a member of the community who would be cared for by Lewis students for up to a year. Many Lewis faculty became well-known for their contributions to education and society, including Carman, who helped create the first educational accreditation board which became the North Central Association of Colleges and Schools, and Ethel Percy Andrus, who became the first female high school principal in the state of California and founded the AARP.
Lewis/Armour merger
Despite success on many fronts for each Armour Institute and Lewis Institute, the Great Depression and changing educational times left both looking for ways to expand and relieve debt. In the late 1930s, the Board of Trustees at Armour was expanded greatly, with many Chicago industrialists and businessmen joining the Board to increase both funding and notoriety. However, it was a proposal from Lewis’ Chairman Alex Bailey to Armour President Henry Townley Heald and Board Chairman James Cunningham that would lead to the birth of IIT. While Armour’s faculty and trustees supported the merger, some Lewis faculty and alumni opposed it, feeling that Lewis’ legacy would be forgotten in the new school. In fact, it was Armour’s campus that became the permanent home of the new school, and Lewis’ campus was used as a civic building by the City of Chicago before the campus was leveled and the United Center eventually constructed. The resistance by Lewis supporters led to a court battle, in which the original will of Allen C. Lewis had to be dissolved. Lewis and Armour completed the merger in 1940, and the fall of 1940 marked the first academic year for the new Illinois Institute of Technology.
Growth and expansion
IIT continue to expand after the merger. As one of the first American universities to host a Navy V-12 program during World War II, the school saw a large increase in students and as a result, had to expand the Armour campus beyond its original 7 acres. Two years before the merger, German architect Ludwig Mies van der Rohe joined Armour to head Armour and the Art Institute of Chicago’s architecture program. The Art Institute would later pull out of the program. Mies was given the task of designing a completely new campus, and the result was a spacious, open, 120 acre campus set in contrast to the busy, crowded urban neighborhood around it. The first Mies-designed buildings were completed in the mid-1940s, and construction on what is considered the "Mies campus" continued until the early 1970s.
Engineering and research also saw great growth and expansion from the post-war period until the early 1970s. Fluid dynamicist John T. Rettaliata, whose research accomplishments included work on early development of the jet engine and a seat on the National Aeronautics and Space Council, was president of IIT during its period of greatest growth from 1952 until 1973. The period saw IIT as the largest engineering school in the United States (as a feature in the September 1953 edition of Popular Science pointed out). IIT was the home of many research organizations, including IIT Reseach Institute, formerly Armour Research Foundation and birthplace of magnetic recording wire and tape and both audio and video cassettes, as well as the Institute for Gas Technology and American Association of Railroads among others.
State Street VillageThree colleges merged with IIT after the 1940 merger of Armour and Lewis: Institute of Design (ID) in 1946, Chicago-Kent College of Law in 1969, and Midwest College of Engineering in 1986. IIT’s Stuart School of Business was founded by a gift from Lewis Institute alumnus Harold Leonard Stuart in the 1960s, and joined Chicago-Kent at IIT’s Downtown Campus in 1992; it phased out its undergraduate program (becoming graduate-only) after Spring 1995. (An undergraduate business program focusing on technology and IIT’s Interprofessional Projects program was launched in Fall 2004, but is administratively separate from the Stuart School and is housed on the Main Campus.) The Institute of Design, once housed on the Main Campus in S.R. Crown Hall, also cut its undergraduate programs and moved downtown in the early 1990s.
Today
McCormick Tribune Campus CenterEnrollment and financial decline from the mid-1970s through the early 1990s threatened the school so much that leaving the Mies campus behind and moving to the Chicago suburbs was considered by the National Commission on IIT in 1994. Construction of a veritable wall of high-rise Chicago Housing Authority projects replaced virtually all of IIT’s neighbors in the 1950s and 1960s, a well-meaning but flawed attempt to improve conditions in an economically declining portion of the city. One of the most notorious of these high-rise complexes, Stateway Gardens, was located just south of 35th Street, the southern boundary of campus. The past decade, though, has seen a redevelopment of Stateway Gardens into a new, mixed-income neighborhood dubbed Park Boulevard begin; the completion of the new central station of the Chicago Police Department a block east of the campus; and major commercial development at Roosevelt Road, one Green Line stop north of campus, and residential development as close as Michigan Avenue on the east boundary of the school.
Today, Illinois Institute of Technology is experiencing a resurgance both nationally and in the Chicagoland area. Bolstered by a $120 million gift in the mid-1990s from IIT alum Robert Pritzker, chairman of IIT’s Board of Trustees, and Robert Galvin, former chairman of the board and former Motorola executive, the university is in the midst of a physical rennovation and revitalization campaign for the Main Campus. The first new buildings on the Main Campus since the "completion" of the Mies Campus in the early 1970s were finished in 2003 – Rem Koolhaas’s McCormick Tribune Campus Center and Helmut Jahn’s State Street Village. S.R. Crown Hall saw renovation in 2005, and Wishnick Hall is currently under work. Undergraduate enrollment has breached 2,000 after reaching a low point of 1,500 in the mid-1990s, and plans are to reach 2,500 by 2010, as estimate that is looking increasingly conservative. Chicago-Kent College of Law has been recognized as one of the top law schools in the Midwest, with leading faculty in international and technology law. Stuart Graduate School of Business, though low on students, boasts the 11th ranked Finance/Financial Markets program in the world as ranked by Global Derivatives magazine. Older programs are still strong, as seen by strong recent growth in the College of Architecture and steady enrollment in the same period for other units. New programs including Biomedical Engineering, "techno-business," and Journalism of Technology, Science, and Business have helped to bring more modernized education to the school still dominated by engineering and architecture programs, the traditional domain of tech schools. To further boost this focus on biotechnology and the melding of business and technology, University Technology Parkis planned to begin construction soon, by remodeling former Institute of Gas Technology and research buildings on the south end of the Main Campus.
Noted alumni
Valdas Adamkus, President of the Republic of Lithuania
Dorothea Brande, writer
Marvin Camras, inventor (magnetic recording tape), educator
Roger Chaffee, astronaut (did not graduate from IIT, but attended his first year and was a member of Phi Kappa Sigma fraternity)
Alvin V. Cheeks, businessman, minister
Martin Cooper, inventor (cell phone)
Mark T. Diganci
Jack Dongarra, University Distinguished Professor of Computer Science, University of Tennessee
James Ingo Freed, architect
Julius Hoffman, attorney and judge
Hans Hollein, Pritzker Prize-winning Austrian architect (attended IIT for one year)
Alfred G. Holtum, engineer
Yasuhiro Ishimoto, photographer
Helmut Jahn, architect
Martin C. Jischke, president of Purdue University
Phyllis Lambert, architect
Jan Lorenc, designer
Tim Michels, businessman, politician
Sam Pitroda, businessman
Robert Pritzker, businessman
Grote Reber, inventor (radio telescope)
James G. Roche, former U.S. Secretary of the Air Force
Vincent Sarich, educator
Jack Steinberger, physicist (Nobel Laureate, attended for two years)
James Young, musician
Rajinder singh ji, noted spritual leader